From the results of the measurement of photoelectron yield excited by ultraviolet synchrotron radiation light, the high resolution electron microscopic observation, and the high energy ion beam analysis, chemical vapot deposited diamond films both of (111) and (100) faces, and also polycrystalline films showed zero or negative electron affinity after hydrogenation of their surfaces. A proper treatment for oxidation or oxygen adsorption on their surfaces, their electron affinities were changed to be positive. The electron affinity was reduced again by irradiation to the ultraviolet light because of desorption of oxygen. These phenomena was thought to be due to the potential change of the electrical double layr induced by adsorption. It was also pointed out that the as-grown surface of diamond films chemical vapor deposited from hydrocarbon gases diluted with hydrogen had a defect rich layr on the surface, and that it was important to remove the defect layr.Device structures of the elect
… Moreron emitters similar to transistors and fabrication processes for them were proposed. Some electron emitter devices having the Schottky junction structure was demonstrated using diamond thin films. A device of polycrystalline diamond film performed electron emission at an efficiency of several percents, where the efficiency was the ratio of the emission current to the diode current, although the total emission current was sitll small. From the fact that the emission current and the diode voltage showed a liner relation in the F-N plot, it was suggested that there was a process of electron tunneling of some potential for the electron emission. It was also observed that the efficiency changed as increased the diode current was. The detail of electron emission process has not clarified yet because of different changing in the efficiency for each device. It was concluded that the improvement of thinning process to obtain a flat surface, the improvement of crystalinity, and stabilization of negative electron affinity surface were necessary to increase the emission current and improve the efficiency. Less